Rare project developers

[Alexander Gall <>]

On Tue, 15 Mar 2022 14:21:57 +0100, mc36 <> said:

> hi,
>> 
>>> but since the state message will only have to deal with the (no)shutdown 
>>> state finally,
>>> what if we move all the parameters from it to the new message?
>>> i mean the following:
>>> state id 0/1 --- just to indicate the shutdown state
>>> ports_add/del/mod id speed etc --- to indicate the port config change
>> 
>> I would simply add the admin state to the port_add/mod messages. If
>> none of the other parameters change, it should be ok to send, for
>> exmaple, a "port_mod id 1/0 <unchanged parameres>" message to just
>> change the admin status.
>> 
>> The forwarder probably needs to be a bit smart about port changes
>> anyway. E.g. I'm not sure one can change the FEC mode without first
>> removing the interface. The forwarder needs to understand things like
>> that to perform the proper sequence of updates.  But it shouldn't have
>> to concern freerouter. It can simply send a port_mod message and leave
>> the details to the forwarder.
>> 
> right now, imho the forwarder could blindly follow the commands....

I see. It makes sense to stick to that principle. Then we accept that
freerouter may need to be aware of certain restrictions that apply
when updating certain elements in the data plane. E.g. it may have to
make sure that messages are sent in a particular order.

> state id 0/1 is just to shut/noshut
> port_add/del/mod id speed etc... are only sent on (no) export-port, or 
> change in the parameters...
> that is, these messages should add/remove from the ports table in tofino...
> in the case of change, you get the mod, in case of no export, you
> get the del, in case of freshly added port, you get the add

Ok.

> ... if you wish, i can dissect the mod to a del followed by an
> add...

Yes, I think that would put us on the safe side in case some changes
can't be made unless some other condition holds (like changig FEC
requires the port to be disabled).

> in any case, the state and mtu messages are sent in the order i thing the 
> tofino would need:
> shut before ports_del, and noshut followed by a ports_add, and ports_mod 
> surrounded by 2 state messages...

There can't be anything before ports_add, I think, since the port
simply does not exist before it's added. But maybe I misunderstand.

-- 
Alex